As a variable displacement compressor provided in a refrigeration cycle, etc., an inclined plate type compressor, for example, a variable displacement inclined plate type compressor added with a clutchless function is known. This variable displacement inclined plate type compressor is formed, for example, as depicted in FIG. 1. Namely, variable displacement inclined plate type compressor 1 has a spindle 2 and an inclined plate 3 provided to be inclinable relative to spindle 2, and the inclined plate 3 is rotated together with spindle 2 in a crank chamber 6 via a rotor 4 fixed to spindle 2 and a link mechanism 5. A pair of shoes 7, 7 are provided in a recessed portion 9 formed at one end of a piston 8 so as to hold inclined plate 3 therebetween, and piston 8 coupled with inclined plate 3 through the pair of shoes 7, 7 is reciprocated accompanied with the rotation of inclined plate 3. The quantity of stroke of piston 8 is determined depending on the inclination angle of inclined plate 3, thereby determining the displacement of compressor 1. Namely, when the inclination angle of inclined plate 3 is maximum, the displacement becomes maximum, and when the displacement is minimum, the inclination angle of inclined plate 3 is controlled at a condition of almost zero degree. Where, symbol 10 in FIG. 1 indicates a suction chamber of a fluid (for example, refrigerant) to be compressed, and symbol 11 indicates a discharge chamber of the compressed fluid, respectively.
In the above-described variable displacement inclined plate type compressor, because the inclination angle of inclined plate 3 becomes almost zero degree when the displacement is minimum and the stroke of piston 8 also becomes almost zero, the inertial resistance and the sliding resistance of the piston approaches zero as much as possible. On the contrary, shoe 7 always slides relatively to inclined plate 3, and it is known that the power consumption due to the viscosity resistance of lubricating oil.
In order to improve the lubricating performance on the sliding surface of the inclined plate, a structure is known wherein a plurality of grooves extending in the radial direction of the inclined plate are provided on the inclined plate, in particular, on the sliding surface with the shoe (Patent document 1). In this structure, however, a gap between the shoe and the inclined plate may discontinuously vary by the grooves extending in the radial direction of the inclined plate, and at worst, the shoe may float relative to the inclined plate. As the result, the operation of the piston may become unstable, and the property and reliability of the compressor may be reduced.
Patent document 1: JP-A-8-159024